Code Style Guidelines for Open-Notebook: Python and TypeScript Standards

Open-Notebook enforces automated code quality through Ruff, Isort (Black profile), and MyPy for Python (88-character line limit), plus ESLint and Prettier for the TypeScript/React frontend (2-space indentation), all configured in pyproject.toml and frontend/eslint.config.mjs.

The open-notebook repository maintains strict code style guidelines to ensure consistency across its Python backend and TypeScript frontend. These standards are fully automated via configuration files and CI pipelines, eliminating manual formatting debates. Contributors must adhere to the rules defined in pyproject.toml and frontend/eslint.config.mjs to pass mandatory linting checks.

Python Backend Code Style

The Python backend relies on Ruff for linting, Isort for import sorting, and Black for formatting. All tool configurations reside in the root [pyproject.toml](https://github.com/lfnovo/open-notebook/blob/main/pyproject.toml).

Line Length and Import Ordering

Maximum line length is 88 characters, optimized for Black's formatting defaults. Isort organizes imports into three distinct groups separated by blank lines: standard library, third-party packages, and local application modules.

import os
import json

import httpx
import numpy as np

from open_notebook.utils import text_utils, graph_utils

Linting Rules and Per-File Ignores

Ruff is configured under [tool.ruff.lint] to check specific error families (E, F, I), while explicitly ignoring:

• E501: Line too long (handled by the 88-character limit)
• E402: Module-level import not at top (required for Streamlit pages)
• E722: Bare except clauses
• F401: Unused imports (allowed for type hints)
• F541: F-strings without placeholders
• F841: Local variables assigned but never used

Per-file ignores in pyproject.toml exempt Streamlit UI components from the E402 rule:

[tool.ruff.lint.per-file-ignores]
"app_home.py" = ["E402"]
"pages/**/*.py" = ["E402"]

Type Checking with MyPy

MyPy runs strict type checking against the codebase but excludes Streamlit UI modules via configuration overrides:

[tool.mypy.overrides]
module = "pages.*"
ignore_errors = true

Frontend Code Style (TypeScript/React)

The Next.js frontend uses ESLint and Prettier for code quality, defined in frontend/eslint.config.mjs.

ESLint and Prettier Configuration

ESLint extends Next.js and React recommended settings with these enforced rules:

• 2-space indentation
• Semicolons required
• No unused variables (no-unused-vars)
• React Hooks rules (react-hooks/rules-of-hooks)

Prettier integration runs with these defaults:

• Print width: 80 characters
• Trailing commas: all
• Single quotes: true

TypeScript Strict Mode

The [frontend/tsconfig.json](https://github.com/lfnovo/open-notebook/blob/main/frontend/tsconfig.json) enables strict mode, noImplicitAny, and exactOptionalPropertyTypes to ensure type-safe code throughout the React application.

Automated Enforcement

Continuous Integration blocks merges that fail style checks. For the backend, CI runs:

ruff check .
ruff format --check .

For the frontend, CI executes:

eslint . --ext .js,.jsx,.ts,.tsx
prettier --check .

Pre-commit hooks automatically format and lint code on every local commit after running pre-commit install, ensuring violations are caught before submission.

Summary

• Python standards: 88-character lines, Ruff + Isort (Black profile), MyPy type checking with Streamlit exemptions
• Frontend standards: 2-space indentation, ESLint + Prettier integration, strict TypeScript compiler options
• Configuration files: pyproject.toml (Python), frontend/eslint.config.mjs and frontend/tsconfig.json (Frontend)
• Enforcement: CI pipelines and pre-commit hooks prevent style violations from entering the main branch

Frequently Asked Questions

What is the maximum line length for Python code in open-notebook?

Python code must not exceed 88 characters per line. This limit is configured in pyproject.toml to align with Black's default formatting standard, balancing readability with modern screen widths while working seamlessly with the Isort Black profile.

How are imports ordered in the Python backend?

Imports are automatically sorted by Isort using the Black profile, grouping them into three categories: standard library imports, third-party packages, and local application modules. Each group is separated by a blank line, and the tool runs automatically via pre-commit hooks or CI.

Why does the project ignore E402 errors in Streamlit pages?

The E402 error (module-level import not at top) is ignored for files matching app_home.py and pages/**/*.py because Streamlit applications often require configuration statements or page setup code before importing certain modules. The pyproject.toml explicitly configures these per-file ignores under [tool.ruff.lint.per-file-ignores].

How do I ensure my code passes the style checks before submitting a PR?

Run pre-commit install to install git hooks that automatically lint and format your code on every commit. You can also manually run ruff check . and ruff format . for Python, or eslint . and prettier --check . for frontend code to verify compliance before pushing changes to the repository.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}